Furnace construction for heat treating upright strip material including vertically adjustable quench blocks



United States Patent Herbert W. Westeren Barrington;

Vincent Scotto, Warwick, R.I. 689,457

Dec. 1 l, 1967 Dec. 15, 1970 C. I. Hayes Inc.

Cranston, 11.1.

a corporation of Rhode Island Inventors Appl. No Filed Patented Assignee FURNACE CONSTRUCTION FOR HEAT TREATING UPRIGHT STRIP MATERIAL INCLUDING VERTICALLY ADJUSTABLE QUENCII BLOCKS 9 Claims, 11 Drawing Figs.

Int. Cl C2ld 9/56 Field of Search 266/3, 4;

[56] References Cited UNITED STATES PATENTS 2,131,505 9/1938 Garsson 266/3X 2,209,674 7/1940 Burish l48/143X 2,371,459 3/1945 Mittelmann... 148/144X 2,510,462 6/1950 Christenson 266/3X 2,6795 74 5/1954 Wade 266/3X 3,119,534 1/1964 Lehnert.. 226/199X 3,355,159 11/1967 Ayers 266/3 Primary Examiner- Robert D. Baldwin Attorney-Salter & Michaelson ABSTRACT: A furnace for heat treating strip material wherein the strip material is guided through the furnace in a substantially upright position and is properly tensioned during the movement therethrough so as to prevent undue distortion, a quench station being located downstream of the furnace heating chamber and being adjustable to compensate for different widths of the strip material that is being heat treated and to provide for proper tension of the strip material as it moves through the furnace heating chamber and quench station.

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INVENTORS. I HERBERT w. WESTEREN BY VINCENT SCOTTO ATTORNEYS FURNACE CONSTRUCTION FOR HEAT TREATING UPRIGHT STRIP MATERIAL INCLUDING VERTICALLY ADJUSTABLE QUENCH BLOCKS BACKGROUND OF THE INVENTION Although the present invention relates to a furnace for heat treating various forms of strip material, it has particular application in the heat treating of band saw blade stock. The prior known furnaces for heat treating band saw blade stock have generally produced satisfactory results, although they have been unpredictable in operation and oftentimes resulted in blades that had uneven edges or a high degree of camber along the edges. It is readily understood that a hardened blade which is either short or long on the teeth line presents a difficult problem for the saw manufacturer because of the requirements of moving the band saw blade at high speeds and therefore heat treating the blade has required special skills and equipment theretofore. Moreover, in recent times, band saw blades have been manufactured in two parts, the root of the blade being formed of one material and the tooth portion being formed of another material. In this kind of band saw blade the root and tooth portions are joined together by any suitable technique, and the joined band saw blade is then moved through a furnace for hardening of the joined blade portions. Because of the formation of these latter-type band saw blades of two different metal materials, the heretofore known furnaces employed in the heat treatment thereof have not always been able to produce consistent results, which has resulted in inferiorly hardened blades. Furthermore, since it was necessary to protect the blade teeth it was difficult feeding the blade stock without contacting the blade teeth and causing damage thereto.

SUMMARY OF THE INVENTION The present invention provides for the heat treatment of strip material, such as band saw blade stock, and is substantially continuous in operation. The band saw blade stock is withdrawn from a reel and is fed through the furnace heating chamber with the teeth thereof facing upwardly so that the plane of the blade is substantially vertical and thereby providing for protection of the blade teeth. The blade stock is guided through the heating chamber by work guides which are externally adjustable to accommodate various stock sizes without the requirement of cooling the furnace or purging the conditioning atmosphere that is introduced into the furnace during the heat treating operation. Located downstream of the furnace heating chamber is a unique quench assembly which insures that the strip material is properly quenched so that it is free of distortion. As the heat treated strip of blade stock leaves the furnace hot zone it passes through the quench zone and is moved between two water-cooled quench blocks in such a fashion that the set teeth therein protrude upwardly of the quench blocks and are thus protected against damage. The blade stock further rides over a hardened steel plate in the quench zone and makes point contact therewith. By causing the strip material to ride over the hardened steel plate, proper tension is maintained on the blade stock, and thus distortion of edge camber of the blade is prevented. The entire quench assembly is also adjustable to compensate for different widths of the strip material as it passes through the quench zone.

Accordingly, it is an object of the present invention to provide a furnace for heat treating strip material that includes a quench assembly that not only provides for proper quenching of the strip material but further ensures that the strip material is maintained at proper tension to avoid distortion thereof.

Still another object is to provide a furnace for heat treating a strip material, such as band saw blade stock, in which the blade stock is continuously moved through a heating chamber and is maintained at proper tension'during the heat treating and quenching operations.

Still another object is to provide a quench assembly for use in a furnace for heat treating strip material, wherein means are provided for adjusting the quench assembly to compensate for different widths of the strip material, additional adjustable means being further provided for locating a contact plate over which the strip material passes in such position that the strip material is maintained at proper tension to prevent distortion of edge camber.

Other objects, features and advantages of the invention will become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.

DESCRIPTION OF THE DRAWINGS In the drawings which illustrate the best mode presently contemplated for carrying out the present invention:

FIG. 1 is a side elevational view of the furnace construction embodied in the present invention;

FIG. 2 is a top plan view of the furnace construction;

FIG. 3 is a fragmentary side elevational view of a guide roller and bearing member that are located upstream of the furnace heating chamber;

FIG. 4 is a longitudinal vertical sectional view of the furnace heating chamber;

FIG. 5 is a sectional view taken along line 5-5 in FIG. 4;

FIG. 6 is a sectional view taken through the furnace heating chamber and showing one of the guide member assemblies located therein;

FIG. 7 is a side elevational view of the quench assembly located on the downstream side of the furnace heating chamber;

FIG. 8 is a front elevational view of the quench assembly shown in FIG. 7

FIG. 9 is a front elevational view with parts shown in section of the quench blocks that are formed as part of the quench as sembly; 7

FIG. 10 is a side elevational view with parts shown in section of the quench blocks illustrated in FIG. 9; and

FIG. 11 is an enlarged fragmentary sectional view of the adjustment means for the contact plate located between the quench blocks.

DESCRIPTION OF THE INVENTION Referring tow to the drawings and particularly to FIGS. 1 and 2, the furnace construction embodied in the present invention is generally indicated at 10 and as shown includes a feed table 12 and a discharge table 14. As will be described hereinafter, the furnace construction 10 is adapted for heat treating strip material, such as band saw blade stock indicated at 16 in FIG. 3. Although the operation of the furnace con struction 10 will be described in connection with the heat treating of band saw blade stock, it is understood that other forms of strip material may be heat treated by the furnace construction 10 without departing from the spirit of the invention.

As shown more clearly in FIG. 2, a feed reel 18 is mounted for rotating movement on the table 12, and the strip material 16 is removed from the reel 18 for passage through a heating chamber generally indicated at 20. After the heating opera tion, the blade stock emerges from the heating chamber 20 for passage through a quench assembly generally indicated at 22 and thereafter is wound on a reel 24. The drive mechanism for moving the strip material from the reel 18 to the reel 24 is located within the table 14 and is drivingly interconnected to the reel 24. It is understood that as the reel 24 is rotated, the strip material 16 is withdrawn from the reel 18 for passage through the heating chamber 20 and quench assembly 22. Alternate reels 26 and 28 are mounted on the tables 12 and 14, respectively, and are adapted to be placed into operation for transfer of blade stock through the heating chamber 20 when the blade stock wound on the reel 18 is completely removed therefrom. It is understood that the movement of the blade stock 16 as it passes from the reel 18 onto the reel 24 is continuous in operation. As the end of the blade stock 16 unwinds from the reel 18, it is attached to the lead end of the blade stock wound on the reel 26. The blade stock on the discharge table is then cut and attached to the reel 28, after which the operation proceeds in a continuous manner as previously described.

Since the blade teeth on the blade stock are set and are relatively soft before hardening, it is imperative that they be protected during the heat treating and quenching operations. It is for this reason that the blade stock 16 is fed through the apparatus with the teeth thereof facing upwardly so as to avoid engagement with the feeding members. Further sufiicient tension is applied to the blade stock as will be described that maintains the teeth in proper oriented position.

in order to maintain tension on the blade stock 16 prior to passage into the heating chamber 20, a pair of guide rollers indicated at 30 and 32 are provided and are mounted on the table 12 adjacent to a hardened block 34. As illustrated in FlG. 3, the guide rollers 30 and 32 are pitched such that the axes thereof are directed downwardly and forwardly so that there is a vertical component of force that directs the blade stock 16 into engagement with the hardened block 34 just prior to the entry of the blade stock into the heating chamber 20. The rollers 30, 32 thus prevent the blade stock from lifting as it enters the heating chamber and, as will be described,

the rollers 30, 32 cooperate with additional guides and a contact plate to provide the proper tension for the blade stock 16 as it is fed through the heating chamber 20'and quench assembly 22. Additional guide rollers 36 and 38 are also provided on the table 14 and are downwardly pitched to urge the blade stock downwardly as it is received and prior to winding on the reel 24.

Referring now to FIGS. 4 and 5, the heating chamber 20 is shown including an outer casing 40, inside of which a high quality insulating material indicated at 42 is disposed in a convenient manner to define an elongated heating area 44 that is substantially rectangular when viewed in. cross section. Located in the heating area 44 are two heating elements 46 that are hung from hanger elements 48 that are secured in the furnace heating chamber walls. The heating elements 48 are located in spaced-apart opposed relation and are sinuously wound, as shown in FIG. 4, to extend substantially the length of the heating area 44. The entrance and exit ends of the heating chamber 20 are fitted with insulated end caps 50 and 52 which form an atmosphere-tight seal with the furnace casing 40. An atmosphere such as dissociated ammonia is adapted to be introduced into the heating chamber for circulation in the heating area 44 so as to provide a protective environment for the blade stock as it passes through the heating area 44. By providing the sealed heating chamber and introducing the protective atmosphere into the heating area, a muffle, as heretofore used in furnaces for heat treating strip material, is

avoided.

In order to guide the blade stock intcriorly of the heating chamber 20, a plurality of work guides generally indicated at 54 are provided and extend upwardly through the bottom-of the furnace wall and into the elongated heating area 44. Refer ring now to FIG. 6, one on the internal work guides 54 is illustrated and as shown comprises an elongated tubular element 56, in the uppermost end of which a V slot 58 is formed for receiving the bottommost edge of the blade stock 16 as it passes through the furnace heating area. The tubular member 56 extends through the insulation of the heating chamber and is connected by a pin 60 to a rod 62. Threadably connected to the lowermost end of the rod 62 is a bolt 64 that is also received in the upper end of a rod 66 of a toggle clamp assembly generally indicated at 68. The toggle clamp assembly 68 further includes a bracket 70 through which the rod 66 extends, the bracket 70 being joined to a frame member 72 by the bolts 74. A handle 76 is interconnected to the rod 66 through a connector 75 that is connected to the bracket 70. Upon pivotal movement of the handle 76, the connector 75 is toggled to an over center position to lower the rod 66, rod 62 and tubular element 56. The tubular element 56 is also adjustable vertically independently of the toggle clamp assembly 68 by means of the threaded bolt 64. As shown in FIG. 6 a stop and the rod 62 in the heating chamber 20, a water cooled jacket 80 is provided and is formed with an internal bore through which the rod 62 and the tubular element 56 extend. The jacket 80 is joined to a plate 82 that is fixed to the underside of the furnace housing 40 by clamps 84 and nut and bolt units 86. An O-ring seal 88 is located in an annular groove formed in the rod 62 and provides a seal for the vertically adjustable rod 62 and the tubular element 56 joined thereto. An insulating brick 90 and insulating material 92 are disposed within the tubular element 56 and tend to reduce heat transfer from the interior of the heating area 44 exteriorly of the heating chamber. The water cooled jacket 80 also tends to dis sipate any heat that is radiated from the heating area through the tubular element 56.

in setting up the unit for operation, the work guides 54 are retracted as the strip material 16 is fed through the heating chamber 20. This is accomplished by moving the handle 76 of the toggle clamp assembly 68 to the lower dotted line position as illustrated in FIG. 6. After the strip material has been fed through the heating chamber 20, the toggleclamp handle 76 is raised to locate the tubular element 56 in the guide position. The tubular element 56 and rod 62 are thereafter vertically adjusted by meansof the bolt 64 and nut 78 to properly position the work. guide in accordance with the width of material that is tobe heat treated.

ln heat treating band saw blade stock or similar strip material, the quenching of the strip material as it leaves the heating chamber is extremely critical, since the camber of the stock must be closely controlled to prevent distortion thereof. Further, since the blade stock as it movesthr'ough'theheating chamber 20 is positioned on end in a vertical plane, it also passes through the quenching station 22 in a similar manner. However, as the quenchingof the stock commences,'the differences in'temperature could result in bowing thereof unless the stock is maintained in proper tensioned relation as it moves through the quench station 22. In order to properly quench the band saw blade stock as it is discharged from the heating chamber 20, the quench station includes opposed quench blocks 94 and 96 that are spaced from each other to define a passage 98 therebetween. ltis through the passage 98 that the blade stock 16 moves as it is fed through the quench station. The quench blocks 94 and96 are hollow in construction, as indicated in FIG; 9, to provide for circulation of a cooling medium therethrough and copper shim liners may be placed betweenthe quench blocks ,to enhance heat transfer therefrom to the moving blade stock. The quench blocks 94 and 96are locked in their spaced-apart relation by being fixed to crossbars 100 through. bolts 102. A back plate 104 is fixed to the rear of the quench block s 94 and 96 and is slit to accommodate the moving blade stock. Spaced tracks 106 are secured to the rear wall of the heating chamberand receive the back plate 104 for movement therein as will be described. Welded to the sidewalls of the quench blocks 94 and 96 are vertical and inclined support members 108 and 110. It is seen that the vertical member s 108, inclined members 110 and the quench blocks 94 and 96 are. movable together; with the back plate 104 relative to the. heating chamberto which the tracks 106 are secured. in order toeffect the vertical movement of the quench blocks 94 and 96 so asto receive therebetween different width blades that have been heat treated, an adjust ment screw member 112 is provided and has a hand wheel 113 fixed to the lower end thereof, the, adjustment screw 112 being threadably engaged to a lower bracket 114 that is secured to.

the support members 108. A bracket 116' is located upwardly of the bracket 114 is also secured to the support members 108' and insures that these members are maintained in their spaced-apart relation. The brackets 114 and 116 are formed with openings in the outermost ends thereof through which rods 118 extend, the rods 118 being secured to a fixed support and thus enabling the support members 108 to move with respect thereto. As shown in FIG. 8, the assembly is fixed to a plate 120 that defines the discharge end of the heating chamber, the plate 120 being fixed in position on the vertical beams 122. Couplings 123 are connected to the quench blocks 94, 96 for conducting cooling liquid therethrough and a cover 125 is mounted over the quench blocks to enclose the conditioning atmosphere therein.

In order to prevent distortion of the blade stock- 116 as it passes through the quench station, a hardened steel plate guide 124 is located between the quench blocks 96 and 98. The uppermost edge of the plate guide 124 is tilted slightly to define an angle, the tilt of the plate guide being from the right to the left as seen in FIG. 10. Thus, a point contact for the blade stock 116 is defined by the plate guide 124 that enables the blade stock to be properly tensioned. In order to adjust the vertical position of the plate guide 124, an adjustment bolt 126 extends through the rearwardmost crossbar 100 and is formed with a pin 128 on the uppermost end thereof that engages the lowermost end of the plate guide. As seen in FIG. 11 a nut 130 is mounted on the threaded bolt 126 and provides for adjustment thereof so as to adjust the position of the plate guide 124. It is seen that when the bolt 126 is vertically adjusted, adjacent end of the plate guide 124 will be more or less inclined, depending upon the distortion of the stock that is to be prevented. Thus, if the blade stock tends to bow, the end of the plate guide 124 is raised. On the other hand, if the blade stock has a tendency to hump, then the end of the plate guide 124 must be lowered. In any event, the point contact of the blade stock with the plate guide 124 produces the proper tension in the blade stock as it passes through the quench station to prevent distortion. It is further seen that as the blade stock 16 passes between the quench blocks 94 and 96 and through the guide channel 98, the teeth as formed on the blade stock project above the quench blocks and are thus protected as the blade stock moves through the quench block assembly.

As previously described the heating chamber and quench station have a protective atmosphere supplied thereto to prevent oxidation or decarburization of the blade stock as it passes therethrough. In this connection, a suitable nitrogen purge and gas safety system is also formed as part of the assembly.

In operation of the furnace, the blade stock 16 is introduced into the heating chamber 20 and is fed therethrough for the heat treatment thereof. As the blade stock 16 is discharged from the heating chamber, it passes through the quench block assembly 22 where it is suitably cooled. The blade stock 16 is moved in and on end position wherein the plane thereof is substantially vertical and is guided through the heating chamber by means of the guides 54 and is held in bearing relation in the quench block assembly on the bearing point as defined by the plate guide 124. The plate guide 124 is adjustable to compensate for distortion of the blade stock if it should occur during the heat treating and quenching steps.

While there is shown and described herein certain specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described except insofar as indicated by the scope of the appended claims.

We claim:

1. In a furnace construction for heat treating a continuous length of metallic strip material, a heating chamber in which heating elements are located in spaced-apart relation, a feed station located upstream of said chamber and including means for feeding strip material to said chamber in a substantially upright position, a discharge station located downstream of said chamber and including means for withdrawing said strip material from said chamber, means located between said chamber and discharge station for quenching said strip material after the heat treating operation, said quenching means mcluding a pair of spaced-apart quench blocks that define a quench area therebetween through which said strip material passes as it emerges from said heating chamber, and adjustment means interconnected to said quench blocks in supporting relation for adjusting the vertical position of said quench blocks to accommodate various widths of strip material in said quench area.

2. In a furnace construction as set forth in claim 1, means located interiorly of said heating chamber for guiding said strip material therethrough in a substantially upright position.

3. ln a furnace construction as set forth in claim I, a substantially vertical bearing plate positioned between said quench blocks, said plate being pitched so that the strip material makes substantially point contact therewith as it passes through the quench area.

4. In a furnace construction as set forth in claim 3, means for vertically adjusting said plate between said quench blocks so as to locate the contact point of said plate in that position wherein distortion of said strip material is prevented as it moves through said quench area.

5. In a furnace construction as set forth in claim 4, said adjusting means including an adjustment pin that projects between said quench blocks adjacent to the underside thereof and that engages the underside of said plate for producing the vertical adjustment thereof.

6. In a furnace construction as set forth in claim 5, said quench blocks being substantially hollow in construction and receiving a cooling medium therein for reducing the temperature at said quench area.

7. In a furnace construction as set forth in claim 6, means for introducing a protective atmosphere into said quench area, wherein said strip material is effectively protected during the quenching operation and prior to withdrawing said strip material to said discharge station.

8. In a furnace construction as set forth in claim 1, a pair of opposed guide rollers located at said feed station upstream of said heating chamber, and engaging said strip material in frictional relation, the axes of said guide rollers being inclined toward said heating chamber with respect to the vertical thereby imposing a downwardly directed vertical component of force on said strip material to maintain said strip material in proper oriented position as it enters the heating chamber.

9. In a furnace construction as set forth in claim 2, said guiding means including at least one vertically extending member having a guide slot formed therein for receiving said strip material in guiding relation, means for vertically moving said member to a positive up or down position, and means for adjusting the vertical position of said member in the positive up position to compensate for different widths of said strip material. 

